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see picture, fm tuner, wax on components ?

Discussion in 'Electronic Basics' started by phil, Apr 21, 2004.

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  1. phil

    phil Guest

  2. Don Bruder

    Don Bruder Guest

    It might not be ultra-stong, but it's sufficient to prevent various
    motion and/or deformation of controls/parts that are adjustable, or
    could be "thrown out of whack" by being moved, squashed, or otherwise
    rearranged.

    If you look closely, you'll probably notice that the majority of the
    "waxed" pieces are either adjustable (probably little square metal
    "cans" with a screwdriver hole in the top. Those are slug-tuned coils,
    and turning the slug, deliberately or otherwise, *WILL* alter the tuning
    capability. Ditto little "flat-pack" widgets with what look like screws
    - Tiny trimmer capacitors.) or would be sensitive to being deformed,
    such as naked coils, like the one you describe as being stuffed with a
    wax soaked sponge. These guys can change value dramatically if bent,
    stretched, or otherwise altered even slightly, again changing the
    tuning, and probably not for the better - Unless you *WANT* the radio to
    cease picking up the FM broadcast band, and instead, start tuning in Ham
    radio conversations, TV soundtracks, perhaps even cops, or in ungodly
    improbable circumstances, even cell phone transmissions.

    The wax is all about "locking down" the factory tuning to prevent
    accidental changes that would knock the radio "out of alignment"
     
  3. phil

    phil Guest

    It might not be ultra-stong, but it's sufficient to prevent various
    How is it applied, do they pay someone with a candle to drop wax drops
    at the end of the production line ?
     
  4. Don Bruder

    Don Bruder Guest

    How is it applied, do they pay someone with a candle to drop wax drops
    at the end of the production line ?
    [/QUOTE]

    More likely, the whole board sits in a mold-box, and something filled
    with hot wax just goes <SPOOGE> in the general direction of the board as
    it goes by on the line, without much (if any) interest in exactly where
    any overflow ends up. Wax isn't conductive, so it really doesn't matter
    on any level (other than cosmetic considerations) where any "spatters"
    might land. Of coure, a more sophisicated production line could use
    something that "spooges" through multiple nozzles, with pinpoint
    accuracy. But since most electronic boards are hidden inside some sort
    of pretty casing, the typical consumer is never going to see how pretty
    it is or isn't. Only "weirdos" like you and me, who open up our
    electronic toys to see what makes them tick. :)

    Amusement value:
    The legend "No user servicable parts inside" that appears on so many
    electronic widgets. Guess what, manufacturers... Some of us CAN figure
    out how to run a soldering iron, meter, and other electronic servicing
    equipment, and can indeed service that "unservicable" device, so your
    statement about no user servicable parts is pure baloney. :)

    I've always been amused by that one... Dunno why, but it tickles my
    funnybone.
     
  5. Years ago I used to work in a repair-shop repairing stuff like that.
    And that's exactly what we did to lock-down moveable and sensitive
    components.
     
  6. The link you gave is not availble.

    The wax is used on critical components to reduce the effects of
    vibration to cause microphonic effects with vibration or movement.
    This was done especialy in high frequency circuits, to dampen the
    microphonics, and to also keep the components mechanicaly aligned. The
    physical positions of many of these compoenents is critical for the
    alignment of the circuits involved. I would not advise to mess with
    this.

    Jerry G.
    http://www.zoom-one.com

    --




    More likely, the whole board sits in a mold-box, and something filled
    with hot wax just goes <SPOOGE> in the general direction of the board as
    it goes by on the line, without much (if any) interest in exactly where
    any overflow ends up. Wax isn't conductive, so it really doesn't matter
    on any level (other than cosmetic considerations) where any "spatters"
    might land. Of coure, a more sophisicated production line could use
    something that "spooges" through multiple nozzles, with pinpoint
    accuracy. But since most electronic boards are hidden inside some sort
    of pretty casing, the typical consumer is never going to see how pretty
    it is or isn't. Only "weirdos" like you and me, who open up our
    electronic toys to see what makes them tick. :)

    Amusement value:
    The legend "No user servicable parts inside" that appears on so many
    electronic widgets. Guess what, manufacturers... Some of us CAN figure
    out how to run a soldering iron, meter, and other electronic servicing
    equipment, and can indeed service that "unservicable" device, so your
    statement about no user servicable parts is pure baloney. :)

    I've always been amused by that one... Dunno why, but it tickles my
    funnybone.[/QUOTE]
     
  7. phil

    phil Guest

    The link you gave is not availble.

    If you are using a browser you need to type (cut and paste) the link
    manually. If you are clicking from OE it should work without that.

    b.t.w.
    If you look closely, one resistor (on the left) has a thin copper wire
    wound around it, what could that be.

    n.b.
    This circuit is from the maxitronix am-fm radio kit
     
  8. Don Bruder

    Don Bruder Guest

    If you are using a browser you need to type (cut and paste) the link
    manually. If you are clicking from OE it should work without that.

    b.t.w.
    If you look closely, one resistor (on the left) has a thin copper wire
    wound around it, what could that be.[/QUOTE]

    I'm guessing it's actually a small-value coil that just happens to be
    wrapped on a resistor-like form. Either that, or it is an actual
    resistor, with a small-value coil formed on it. Either way, it's almost
    certainly a carefully tuned item that you don't want to mess around with
    unless you've got the know-how and tools to retune it to whatever value
    it had before you started playing with it. With coils, it doesn't take
    much to change their value in a big way - Sometimes, especially in
    high-frequency work, adding/subtracting turns, or even moving just one
    turn of the coil one wire-width further away from or closer to its
    nearest neighboring turn, is sufficient to change the value of the coil
    dramatically enough to completely de-tune the circuit and cause the
    device it's in to be unusable. (or worse - cause it to continue working,
    but on a frequency so different than intended that it seems to be
    non-operational by all tests that you can apply)
     
  9. Rich Grise

    Rich Grise Guest

    I don't see any wax at all. Unless that translucent glob on the
    left is waxy. It looks just exactly like RTV to me.

    I don't konw what the sponge is, but I'm assuming some kind
    of spacer.

    If you poke that whitish glob with your fingernail, does it leave
    a mark? Or is the stuff rubbery? 'cause that board doesn't have
    any of that tuner wax on it at all.

    (at least not the kind they used last millennium. ;-) )

    Cheers!
    Rich
     
  10. Rich Grise

    Rich Grise Guest

    Not to worry. It's the choke. :)

    Cheers!
    Rich

    I'm guessing it's actually a small-value coil that just happens to be
    wrapped on a resistor-like form. Either that, or it is an actual
    resistor, with a small-value coil formed on it. Either way, it's almost
    certainly a carefully tuned item that you don't want to mess around with
    unless you've got the know-how and tools to retune it to whatever value
    it had before you started playing with it. With coils, it doesn't take
    much to change their value in a big way - Sometimes, especially in
    high-frequency work, adding/subtracting turns, or even moving just one
    turn of the coil one wire-width further away from or closer to its
    nearest neighboring turn, is sufficient to change the value of the coil
    dramatically enough to completely de-tune the circuit and cause the
    device it's in to be unusable. (or worse - cause it to continue working,
    but on a frequency so different than intended that it seems to be
    non-operational by all tests that you can apply)

    --
    Don Bruder - - New Email policy in effect as of Feb. 21, 2004.
    I respond to Email as quick as humanly possible. If you Email me and get no
    response, see <http://www.sonic.net/~dakidd/main/contact.html> Short
    form: I'm trashing EVERYTHING that doesn't contain a password in the[/QUOTE]
    subject.
     
  11. I've seen sponge like material in air wound coils. I thought or
    assumed it was there to keep down microphonics.

    RTV probably serves the same purpose as the wax, though who knows if
    it affects the coils differently. But the disadvantage is that
    it's not nearly as easy to remove if needed. You can always heat
    up the wax and it will melt, but getting RTV off usually requires
    some scraping, and that scraping may damage the coil you are
    trying to get to.

    Michael
     
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